Currently, avionics computers cooled by aeraulic means simply use fans located on the front face or at the level of the bottom face of said computers.
Until recently, there was no real need to seek to optimize this type of aeraulic cooling. In practice, the power dissipated inside the computers was relatively low, and hot spots did not appear on the electronic modules requiring any particular attention. Simple ventilation by a stream of air injected into the computers was sufficient to ensure that they operated correctly.
These days, the power density dissipated at the core of avionics computers is greatly increasing. The electronic components used, increasingly small and increasingly powerful in terms of computation capabilities, also dissipate more and more power in restricted spaces.
Initially, increasing the size or the number of fans present in the computers was envisaged in order to better cool them. However, this simplistic solution is unsatisfactory: it raises problems of bulk and acoustic noise.